Paragryllinae, Desutter-Grandcolas, 1987

Timm, Vítor Falchi, Martins, Luciano De Pinho, Acosta, Riuler Corrêa, Szinwelski, Neucir, Pereira, Marcelo Ribeiro, Costa, Maria Kátia Matiotti Da & Zefa, Edison, 2021, Trends of karyotype evolution in the Neotropical long-legged crickets Phalangopsidae (Orthoptera, Grylloidea), Zootaxa 4938 (1), pp. 101-116 : 108-113

Paragryllinae

Ubiquepuella telytokous is the only species that presents thelytokous parthenogenesis in Grylloidea ( Fernandes et al. 2015), and the absence of meiotic divisions, as well as haploid nuclei in the ovarian tissues, show that the oocytes maturation occurs through mitotic division, thus characterizing ameiotic parthenogenesis ( White 1973; Normark 2014). The chromosome morphology of this species hint predominance of pericentric inversions and/or reciprocal translocations in the karyotype derivation process, revealed by the morphology of the bivalent pairs 4, 5 and 9, all of them becoming close to acrocentric.

Individuals from both studied locations present karyotypes sharing the same secondary constriction in the pair 6, bearing satellite with size heteromorphism, which one is common in Grylloidea species ( Mafla & Cevallos 1989; Zefa 1999; Yoshimura 2006; Schneider et al. 2010; Palácios-Gimenez et al. 2015a). The small differences in the centromeric index values here obtained when compared to the Fernandes et al. (2015) results are due to the measurement criteria adopted by each author. Thus, we assume that the karyotype of this species is similar among individuals from studied populations.

Adelosgryllus rubricephalus (Adelosgryllini) presents karyotype with 2n = 19, X0♁ for individuals from the State of São Paulo / Brazil, with a pair of submetacentric chromosomes, and 2n = 17, X0♁, with two pairs of submetacentrics for an individual from Foz do Iguaçu/ PR ( Mesa & Zefa 2004). The reduction in the chromosome number was due to the centric fusion between two pairs of acrocentric homologues, as shown in the karyotypes presented by Mesa & Zefa (2004).

The karyotype of A. rubricephalus from Foz do Iguaçu/ PR described by Mesa & Zefa (2004) with 2n = 17♁ is very similar to those of A. cruscastaneus and A. similis from Crato/CE, all of them with two large metacentric pairs (pairs 1 and 2). On the other hand, the individuals we collected in Iguaçu National Park/ PR (around 30 km from the place where Mesa & Zefa (2004) collected) showed a karyotype of 2n = 19♁, similar to A. rubricephalus from the States of Rio Grande do Sul and S„o Paulo/ Brazil (see Fig. 15 ). Although the heterozygous karyotype for centric fusion was not found in Foz do Iguaçu (as few specimens were analyzed, due to the difficulty of finding these crickets in the field), it is likely that chromosomal polymorphism occurs in the population of this location.

The karyotype similarities among individuals of A. rubricephalus (2n = 17♁) with of the A. cruscastaneus and A. similis (both 2n = 17♁) shows that the karyotype derivation of these species (from 2n = 19♁ to 2n = 17♁) occurred by independent centric fusions. It is still an open question how chromosomal evolution produced similar karyotypes in different species through independent rearrangements.

Laranda meridionalis is the only karyotyped species of this genus, and represents the basal karyotype among the Paragryllinae crickets, with 2n = 21, X0♁, with chromosomal morphology derivation with predominance of pericentric inversions and/or reciprocal translocations.

Figures

FIGURE 15. Distribution of Adelosgryllus’ species citogenetically studied, and their respective karyotypes for each region. SM = submetacentric chromosomes; unmarked chromosomes are all acrocentrics, and X metacentric. Orange and red karyotypes extracted from Mesa & Zefa, 2004 without changes.